[House Document 105-81]
[From the U.S. Government Publishing Office]



105th Congress, 1st Session  - - - - - - - - - - - House Document 105-81


 
                        LAS CRUCES, NEW MEXICO

                               __________

                             COMMUNICATION

                                  from

 THE ASSISTANT SECRETARY OF THE ARMY (CIVIL WORKS), THE DEPARTMENT OF 
                                THE ARMY

                              transmitting

  A REPORT ON THE FLOOD DAMAGE REDUCTION PROJECT FOR LAS CRUCES, NEW 
 MEXICO, PURSUANT TO PUB. L. 104-303, SEC. 101(A)(20) (110 STAT. 3665)





     May 7, 1997.--Referred to the Committee on Transportation and 
                Infrastructure and ordered to be printed
                                     

105th Congress, 1st Session  - - - - - - - - - - - House Document 105-81


                        LAS CRUCES, NEW MEXICO

                               __________

                             COMMUNICATION

                                  from

 THE ASSISTANT SECRETARY OF THE ARMY (CIVIL WORKS), THE DEPARTMENT OF 
                                THE ARMY

                              transmitting

  A REPORT ON THE FLOOD DAMAGE REDUCTION PROJECT FOR LAS CRUCES, NEW 
 MEXICO, PURSUANT TO PUB. L. 104-303, SEC. 101(A)(20) (110 STAT. 3665)





     May 7, 1997.--Referred to the Committee on Transportation and 
                Infrastructure and ordered to be printed


                            C O N T E N T S

                              ----------                              
                                                                   Page
Letter of Transmittal............................................     v
Comments of the Office of Management and Budget..................   vii
Comments of the State of New Mexico..............................  viii
Comments of the Department of Interior...........................    ix
Comments of the Federal Emergency Management Agency..............     x
Report of the Chief of Engineers, Department of the Army.........     1
Report of the District Engineer..................................     5
    Syllabus.....................................................     5
Section 1........................................................     6
    Introduction.................................................     6
    Study Authority..............................................     6
    Purpose and Scope............................................     7
    Study Participants...........................................     9
    Prior Studies and Reports....................................     9
Section 2........................................................    11
    Study Area Description.......................................    11
    Socio-Economic Characteristics...............................    11
    History of the Area..........................................    11
    Physical Characteristics.....................................    12
    Environmental Setting........................................    14
    Cultural Resources...........................................    15
    Recreational Resources.......................................    16
    Existing Flood Control Structures............................    16
Section 3........................................................    18
    Problem Identification.......................................    18
    Historical Flooding..........................................    18
    Hydrologic Analysis..........................................    19
    Hydraulic Analysis...........................................    23
    Economic Analysis............................................    29
    Expected Future Without Condition............................    33
Section 4........................................................    34
    Plan Formulation.............................................    34
    Planning Objectives..........................................    34
    Planning Constraints.........................................    34
    Plan Formulation and Rationale...............................    35
    Technical Criteria...........................................    35
    Economic Criteria............................................    35
    Environmental Criteria.......................................    37
    Alternatives Investigated....................................    37
    Screening of Alternatives....................................    43
    Optimization of the Selected Plan............................    45
    Federal Interest.............................................    45
    Special Cost Sharing or Windfall Benefits....................    48
    Description of the Selected Plan.............................    49
    Real Estate Requirements.....................................    50
    Mitigation Requirements......................................    51
    Operation, Maintenance, Repair, Replacement and 
      Rehabilitation.............................................    52
    Recreation...................................................    52
    Cost Sharing Requirements....................................    52
    Financial Analysis...........................................    53
    Project Procedures and Implementation........................    53
    Project Accomplishments......................................    54
    Project Performance..........................................    57
Section 5........................................................    58
    Conclusions..................................................    58
    Disclaimer...................................................    61
Sponsor's Letter of Intent.......................................    62
Public Comments..................................................    65
Environmental Assessment.........................................    70
Fish and Wildlife Coordination Act Report........................    91
Final Environmental Assessment...................................    92


                             LIST OF TABLES                             
                                                                        
 Number                                                                 
                                                                        
2-1      Population Growth of Las Cruces...................        11   
2-2      Pertinent Features of the Las Cruces Dam..........        17   
3-1      Rainfall Amounts Used in Analysis.................        21   
3-2      Impervious Coefficients...........................        22   
3-3      Discharge and Volumes at Concentration Points.....        25   
3-4      Flows and Manning's N--Flow Path 1................        27   
3-5      Flows and Manning's N--Flow Path 2................        28   
3-6      Flows and Manning's N--Flow Path 3................        28   
3-7      Flows and Manning's N--Flow Path 4................        29   
3-8      Flows and Manning's N--Flow Path 5................        29   
3-9      Value of Property Flooded by Event--All Flowpaths.        31   
3-10     Number of Property Units Flooded by Event--All                 
          Flowpaths........................................        32   
3-11     Mean Single Occurrence Damages by Land Use and                 
          Flood Frequency--All Flowpaths...................        32   
3-12     Average Annual Damages and Residuals by Land Use..        33   
4-1      Applicability of Non-Structural Measures..........        39   
4-2      Cost Per Structure for Non-Structural Alternatives        41   
4-3      Total Costs--10 Year Non-Structural Measures......        41   
4-4      Benefits and Costs--Non-Structural Measures.......        42   
4-5      Comparison of Structural Measures.................        44   
4-6      Average Annual Damages and Benefits Including Risk             
          Adjusted Results.................................        46   
4-7      Benefit/Cost Analysis.............................        46   
4-8      Comparison of Costs and Benefits--Selected Plan...        48   
4-9      Project Implementation Costs......................        53   
4-10     System of Accounts--Selected Plan.................        55   
4-11     Project Performance...............................        57   
                                                                        
                             LIST OF FIGURES                            
                                                                        
1-1      Vicinity Map--Dona Ana County, Las Cruces, NM.....         8   
3-1      24-Hour Rainfall Event Summary....................        20   
3-2      Rainfall Hyetograph 1%-Chance Event...............        21   
3-3      Determination of Manning's N Value................        26   
4-1      Optimization Curve................................        47   
                                                                        
                             LIST OF PLATES                             
                                                                        
1.       Study Area and General Plan.......................       123   
2.       Flow Path Locations...............................       124   
3.       Pre-Project 100-Year Flood Plains.................       125   
4.       Selected Alternative--General Plan................       126   
5.       Post-Project 100-Year Flood Plains................       127   
6.       Sub-Area Concentration Points, Federal Interest...       128   
                                                                        



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